Wildlife identification resources

Otter spraint analysis

Moors for the Future have a new Community Science Project, looking for signs of mammals in the uplands, the Tails of the Uplands Survey. (Follow the link for details of how to get involved and training courses available.)

A key target species is the otter, one of our most attractive and endearing mammals, which nearly disappeared from England in the 1960s and 1970s, but which is now starting to recover across much of the animal's former range.

Evidence for otter presence is indicated by a number of signs, one of which is their droppings, known as spraint. As well as indicating presence, analysis of spraint can help us find out what the otters are eating. Traditionally this was done by examining spraint under a low power microscope, and identifying bones (and other undigested material, such as fur and feathers). However, nowadays, more sophisticated methods are available using DNA analysis. However, it is interesting to compare results of both techniques, and I have been examining samples from which DNA has been extracted and sequenced to identify prey items. The genetic analyses were performed at the Molecular Ecology Laboratory at the University of Sheffield as part of the Otterly Amazing project run by the Sheffield and Rotherham Wildlife Trust.

Preliminary results from the DNA-based diet study at the University of Sheffield which included these samples are available on the otter diet study page.

bones found in sample after cleaning and after sorting (focus stacked image)

Suspected field vole jaw fragment found in sample after cleaning and after sorting (focus stacked image)

Contents of sample 3 (suspected otter spraint from the River Don)

Sample 3 mostly consisted of fish remains, largely of smaller fish, judging by the size of vertebrae found. However, there were also four small spherical balls found.

Sample after cleaning

Sample after initial rough sorting

Fish vertebrae found in sample 3

other fish remains found in sample 3 (mainly opercular material and ribs)

Small spherical objects found in spraint (microballs)

Single microball (just less than 1mm diameter)

Sample B (Suspected fox scat from Skye, 20 May 2017)

Sample found in a bay next to a washed up dead sheep and washed up dead deer. Contains mostly fur, and several mammalian bone fragments, as well as what appears to be some vegetable material. Cleaning using steradent tablets did not work well with this specimen, mostly just bleaching the sample. Sample had to be teased apart using dissecting tools.

sample after pouring off ethanol and before cleaning

sample after (unsuccessful) cleaning and before sorting and analysis

fur found in sample after cleaning and after sorting

Bone fragments and vegetable material found in sample. Includes jaw fragment, apparently of a herbivore, possibly rabbit.

Sample D (Sample from Skye - suspected pine marten scat)

Sample contains invertebrate remains, including several beetles, as well as several balls of fibrous material (unidentified).

sample after pouring off ethanol and before cleaning

sample after cleaning and before sorting and analysis

sample after cleaning and after initial sorting

Beetle (Coleoptera) remains found in sample.

Sample L50 (Sample from Skye - suspected otter spraint)

Sample contains mainly crustacean remains as well as a few small fish bones.

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